Q: What's the latest science on going barefoot when we run or walk?

A: Wearing shoes changes how our feet interact with the ground below us, according to a novel new study in the journal Nature.

The study, which echoes some of the research that first popularized barefoot running, finds that walkers move differently when they are barefoot or shod and have differing sensitivity to the ground, potentially affecting balance and joint loading. The results suggest advantages to perambulating with naked feet, not the least of which involves developing calluses.

We humans are born to walk. Shoes, though, are new to us. Archaeological finds indicate that humans first started wearing rudimentary sandals about 40,000 years ago, an eyeblink in our history as a species. People who walk without shoes develop hard, leathery calluses that can reduce sensations of pain when they stride over small obstacles like gravel.

Today, many of us might consider such calluses unsightly and disagreeable. But Daniel Lieberman, an evolutionary biologist at Harvard University, began to wonder recently whether those calluses might have a hidden utility and beauty. 

In Kenya, his team studied 81 men and women. They found that people who had grown up walking barefoot had large, tough calluses.

Lieberman and his colleagues had thought that the hardened skin might block nerves from sensing the ground. But when they measured those nerves’ reactions in people with and without calluses, they found few differences.

Back in Boston, the researchers found that shoes can shake up a walk. When male and female volunteers with shoes strolled on treadmills, the impacts from each stride lingered longer than when they were barefoot.

Such persistent impacts tend to move up and dissipate through our bones and joints, whereas the shorter, sharper jolts created when we walk barefoot are more likely to rise through our soft muscles and tendons, Lieberman said.

The message would seem to be that people who have concerns about their balance or their knees — but not their pedicures — might consider sometimes walking barefoot.

— Gretchen Reynolds, The New York Times